Cell Boundaries Objective: 4B – Investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules

Chp. 7, Section 2 & 4 – Cell Boundaries Animal cell Plant cell Cell / Plasma Membrane Cell walls make up the bulk, roughage, or fiber of our diet, material that we do not have enzymes to digest. (review ENZYMES orally) Cell Wall – provides support & protection, usually made of tough fibers

1. The Cell Membrane Complex barrier separating the cell from it's external environment Holding cytoplasm within cells Regulating substances entering and exiting cells Recognizing other cells Is arranged in a double layer called a Lipid Bilayer – Made up of Phospholipids (a phosphate group & 2 fatty acids)

1. The Cell Membrane "Selectively Permeable" membrane that regulates (like a gate) what passes into and out of the cell

1. The Cell Membrane Cell Membranes are FLUID Lipids and Proteins of the Cell Membrane are always in motion

1. The Cell Membrane Membrane Proteins PROTEIN MOLECULES are EMBEDDED in the Lipid Bilayer HELP to MOVE substances that are large or charged (ions) INTO and OUT of the Cell

1. The Cell Membrane Often have carbohydrates attached to them to serve as I.D. badges that allow cells to recognize each other

1. The Cell Membrane Diffusion Movement of particles from an area of high concentration to an area of low concentration (no energy required) Osmosis Diffusion of water through a selectively permeable membrane

3 different types of Osmosis

3 different types of Osmosis Isotonic The concentration of solutes is the same inside and outside the cell Water moves in and out Hypertonic Solution has a higher solute concentration than the cell Water moves out Hypotonic Solution has a lower solute concentration than the cell Water moves in

Tip to remember: Salt Sucks! Water moves toward the more salty area. H2O Hypertonic Solution

1. The Cell Membrane Facilitated Diffusion / Passive Transport Uses proteins to move molecules through a cell membrane along the concentration gradient (no energy required)

1. The Cell Membrane Active Transport Uses proteins to move molecule against the concentration gradient Requires energy

Exocytosis and Endocytosis Exocytosis – process of a cell releasing materials Endocytosis – process of cell taking materials in Exocytosis

Animal cell Plant cell Cell / Plasma Membrane All we have been talking about today happens with the outer boundary of a cell.

Practice Question Which cell process will move substances against a concentration gradient? [NC08 EOC] A diffusion B facilitated diffusion C osmosis D passive transport E active transport Requires ENERGY

Practice Question What cell membrane structure allows bigger molecules to cross over and also serves as an attachment site for the cytoskeleton? Carbohydrate Phospholipids Cholesterol Protein

What kind of passive transport is shown in the picture? Diffusion Osmosis Facilitated diffusion Active transport